So, what do we make of Chacin? He's just 24-years-old and carries a 3.59 ERA in 346.1 MLB innings pitched. Over the last two seasons, he's put up above league average adjusted-ERA numbers (124, 142 ERA+). But, despite the sparkling ERAs, looking closer at his numbers over the last two seasons, it's clear that Chacin hasn't progressed the way the Rockies had hoped.
In 2010, Chacin made 21 starts for the Rockies and posted the following peripheral numbers: 8.7 SO/9, 2.15 SO/BB, .287 BAbip.
In 2011, in a larger sample of 31 starts, he posted these numbers: 7.0 SO/9, 1.72 SO/BB, .264 BAbip.
These are the important numbers to look at with Chacin. Here, you can see that he wasn't the same pitcher he was in 2010. The strikeouts were way down and he actually led the National League in walks. His control actually got worse as the year went on as he posted a 1.32 SO/BB after the midway point of the season in '11. He's never posted a BB/9 in the big leagues lower than 4.00 and he's never posted one in the minors higher than 3.05. Chacin isn't a pure stuff guy, so we might be able to assume that he's less confident in throwing his stuff over the plate in the majors.
The interesting aspect of Chacin's '11 season was that he pitched so much than he did the year before but also managed for his ERA not to fall completely off the table and stay better than league average. This may not have been his doing, actually, when it appears that Chacin's defense was a lot better at converting his balls in play into outs than they had been the year before. The decrease in BAbip for Chacin's opponents may have been aided by the uptick in ground balls as Chacin saw his GB% climb up and over 50% to 56.3%.
Still, I wouldn't say I'm a believer in Chacin's BAbip and LOB% (Left on base percentage) gains from last year. Generally, a pitcher striking out fewer batters and getting "luckier" on balls in play and strand rate is due for a run of bad luck eventually. Take his FIP (Fielding Independent Pitching) jumping from 3.54 to 4.23 as a warning sign. Going off the way he was hit around by the Giants in the Rockies home opener, I'd say Chacin is in for a very tough 2012 season that will see his luck run out as regression to the mean takes over. His BAbip is almost certain to go back up this season and if he doesn't make some serious gains when it comes to not walking guys, he's going to give up runs in bunches.
There is also the matter of Chacin's declining fastball velocity. During the '11 season, his average fastball velocity was 91.2 mph, which was slightly down from 91.5 mph in '10. In '11, Chacin had only two games where his average fastball velocity dipped below 90 mph. This season, he has made one start and already has one of these games as his average fastball velocity was just 89.4 against the Giants on Monday. This is where we make the jump from concerned to alarmed. If there's something wrong with Chacin and his stuff is suffering because of it, then all bets are off.
Chacin is a perplexing young pitcher who could be a number two pitcher for the Rockies if he's totally healthy. We won't really know if he can do that until he does it and I don't anticipate that happening this year. There needs to be an adjustment to his game in some way. He either needs to take away the walks or miss more bats, or both. Until then, keep an eye on those velocity readings. Perhaps they might tell us the real story.